There is presently known transmission line electrical cables which utilize a conductor formed as twisted strands of a conductive material i.e., aluminum or copper etc., wrapped or braided about a steel core. In the past, there have been proposed means of dead ending or splicing the transmission conductors which required separate crimping means for use on the steel core and one on the aluminum components of the line. Since two crimping steps were involved, it suffered such obvious disadvantages as requiring additional time and equipment in addition to being awkward.
In an effort to overcome the requirement of the two crimp method, U.S. Pat. No. 3,996,416 issued Dec. 7, 1976, discloses an aluminum core grip for connecting the core reinforced cable to another cable or to a cable accessory. Illustrated in FIG. 1 herein, is the core grip proposed by the aforenoted patent comprising a single piece element, elongated with a bore, sized to the specific steel core diameter of the cable on which it will be used, lined with grit therethrough. The core grip is provided with three (or four) longitudinally extending radially outwardly directed lobes. To provide the connection, at the end of the cable to be worked, a portion of the conductor is stripped from the cable exposing the steel core for about the length of the core grip. The steel core is then forced into the bore and the cable with the grip therein is inserted into one end of a compression barrel in which at the opposite end is inserted the element (cable, dead end etc.) that the cable is being joined in an end to end relation. The compression barrel is now crimped to effect a splice or dead end connection. The lobes during crimping give way to effect a contact between the cable and the compression barrel.
While having advantages over the two crimp operation, this means of connecting transmission lines suffers several disadvantages. First, a single piece core grip is utilized requiring the steel core to be forced into the bore thereof the diameter of which is sized to the steel core. If the steel core has a poor lay, this may be difficult to accomplish and time consuming.
In addition, it has been found that the absence of sufficient grit in connections of this nature can severly reduce the overall holding strength of the connection. If core slippage results, this leads to an overloading and tensile breaks in the aluminum strands at something less than rated breaking strength of a composite conductor.
Since the single piece device requires a forcing of the steel core into the bore, during this insertion the grit therein tends to become dislodged and lost resulting in an undesirable situation with the possible results aforenoted.
Furthermore, in the three lobe core grip, a specific geometry of the lobes is used to attain the holding function. The geometry is such that the aluminum will collapse and place a compressive force on the steel core, due to the compressive force placed on the compression barrel by external pressure applied by the crimping dies. However, the straightness of a compressed connector is dependent upon uniform longitudinal extrusion of the composite connector which is done in sections. The composite must be origin symmetric in order to insure uniform longitudinal extrusion outwardly from the compression dies. However, without origin symmetry as in the case of the three lobe core grip, the connector composite will tend to bow away from the side containing more material.